Full Depth Reclamation Fly Ash Stabilization MERRILL AIRPORT & - - PowerPoint PPT Presentation

Full Depth Reclamation Fly Ash Stabilization MERRILL AIRPORT & LANGLADE COUNTY AIRPORT (Antigo)

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Pulverize Asphaltic Pavement and Base Course

• Full Depth Reclamation – aka – Cold In-place Recycling [CIR]
• A reclamation technique in which the full flexible pavement section and a

predetermined portion of the underlying materials are uniformly crushed, pulverized, or blended, resulting in a stabilized base course;

• Used to fix irregular cross sections, reflective/alligator cracking, heavy

pothole patching, severe rutting/shoving, and insufficient base strength. Substantial savings can be realized while meeting environmental goals.

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Typical Candidates for Pulverize Asphaltic Pavement and Base Course

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Overview

Cold In-place Recycling [CIR]

Proportioned mixture

• Fly Ash – 10 to 12% by weight (110# per SY)
• Aggregate (Reclaimed Asphalt Base)
• Water – 9 to 12 % typical for optimum density

Mixed in-place and compacted (12” depth for sub-grade

stabilizing; 8” depth for CIR)

Produces a strong and durable pavement base course (300 - 450

psi) for flexible pavements.

Typical cost ranges from $3.50 to $4.00 per SY complete – ready

to pave.

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Fly Ash Storage Hopper (Silo) to Tanker

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Problems Solved by Recycling HMA Pavement & Base

Bridges poor sub-grades and underlying soils. Provides medium to improve drainage. Provides a transitional load-bearing layer between the

pavement layer and the underlying wet and unstable sub-grade soil.

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Base Stabilization – “The Process”

Cold-in-place recycling

begins with pulverizing the existing asphalt pavement and underlying base course.

• Top – Bomag [Light duty]
• Bottom – Wirtgen [Heavy duty]

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Base Stabilization – “The Process”

• Pulverized / blended material

is then re-compacted and graded to proper crown and cross slope.

• In essence, a new base is

created that can either serve as a stable foundation for a new asphalt surface.

• Top – Pulverize, re-grade &

compact.

• Bottom – Evidence of soft &

unstable sub-grade

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Base Stabilization – “The Process”

• Deliver Fly Ash and transfer to

Vane Feeder

• Spread Fly Ash uniformly on the

newly prepared recycled base.

• Vane feeder distributors controls

concentration of ash and controls dust.

• Fly Ash is very fine and tends to

blow about when windy or disturbed

• Top – Tanker truck transfer to vane

feeder.

• Bottom - Spreading Fly Ash.

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Base Stabilization – “The Process”

Reclaimer / Pulverizer follows

water truck, mixing:

Fly Ash, Recycled Base, and Water – injected directly into the

pulverizer

Water is needed to begin the

hydration process similar to cement.

Moisture content is critical to

performance

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Base Stabilization – “The Process”

Water injected directly into the pulverizer

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Base Stabilization – “The Process”

Immediately behind the

mixing process, a vibratory pad-foot roller follows to produce the desired density.

The compacted material is

then graded to final profile, crown and cross slope.

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Base Stabilization – “The Process”

Surface is again

compacted and sealed using a smooth drum or pneumatic roller

Occasionally, the surface is

re-wetted to ensure completion of the hydration process

Hydration will be complete

in 3-4 hours.

Monitoring moisture

content is critical

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Base Stabilization – “The Process”

The new stabilized base is now ready for paving.

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Base Stabilization – “The Process”

• Bottom Asphalt Layer – 106% payment based on densities

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Base Stabilization – “The Process”

Langlade County Airport

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Base Stabilization – “The Process”

• Estimated Costs – Cold In-place Recycling

(Merrill Airport)

1.

Fly Ash application

• Applied at a rate of 120 lb./SY 12” average application depth.
• Very soft areas treated w/ heavier application rate or deeper.
• COST - $68,000

2.

EBS [Excavation Below Sub-grade]

• 18” deep.
• Replace EBS with CABC.
• COST - $132,000

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Base Stabilization – “The Process”

• Estimated Costs – Base Stabilization

(Langlade Co. Airport)

1.

Fly Ash application

• Applied at a rate of 110 lb./SY 12” average application depth.
• Very soft areas treated w/ heavier application rate or deeper.
• COST - $58,000

2.

EBS [Excavation Below Sub-grade]

• 2-feet deep.
• Replace EBS w/ 1.5 ft. borrow material and 0.5’ ft CABC.
• COST - $120,000

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Thank You Questions?